Attached to all the bones and disks in the spine are long, cordlike structures called ligaments. Not as hard as bone but not as soft as muscle, these bands of connective tissue come in almost every size. Some are short, running only between adjacent bones, but some are very long, extending all the way down the length of the spine.
The ligaments have several important functions. They provide support for the spine from the head down to the tip of the tailbone, holding disks and bones and muscles in their proper places. Their main function is to hold the bones together, allowing bending, twisting, and other movements to occur within safe ranges. Because ligaments are somewhat elastic, giving them the ability to stretch a little but not too much, they are perfectly suited for this task. When you bend over forward as far as you can, these ligaments reach the end of their length; they become taut, keeping the bones from moving apart any farther. This is an important function, because it spares other parts of the spine, such as the disks, the burden of holding the bones together -- a damaging task that they are simply not designed to do.
When you are standing straight, the ligaments are at normal length (left).
However, when you bend, rounding your back, the ligaments are stretched
to their maximum length trying to hold the bones together and support
your hanging upper-body weight (right).
Muscles are cordlike structures that are even more elastic than ligaments. Like ligaments, muscles can stretch; unlike the ligaments, muscles also have the ability to contract, or shorten. This is, in fact, what happens when you lift a cup of coffee, throw a ball, or do anything that requires movement of the body. The muscles shorten and lengthen, pulling the bones in different directions to coordinate our movements. When you lift, lower, push, pull, carry, or perform any activity, the muscles are doing the work.
Muscles also work to keep the body from moving when movement is not desired. For example, if you are sitting in a canoe and the canoe starts to tip to the left, your muscles quickly respond by coordinating your body's movement to the right to maintain your balance.
Muscles are true workhorses and can be your back's best friend. When conditioned, your muscles maintain their strength, endurance, and flexibility, which allows the body to move and work with less risk of injury and pain. When working properly, the muscles can greatly reduce the load on the bones, facet joints, disks, and ligaments. In contrast, when the muscles become deconditioned from lack of use or from injury, they tend to lose their size, strength, endurance, and flexibility.
How do muscles work? Basically, when you want to move, your brain sends a message through the nerves to the correct muscle. When the message gets to the muscle, chemicals inside the muscle cause the muscle to shorten. Because the muscle is attached to the bone, this shortening pulls on the bone. If the strength of this shortening is strong enough, the bone, and therefore the body, moves.
When your back muscles are in shape, they support the spine well (left).
When they are weak, the spine can suffer poor posture and possible injury (right).
In the short term, this muscle fatigue may result in nothing more than a little low-level back pain, but if this condition continues day after day, year after year, the back can wear out much faster than it should. If the muscles are not stretched, they can be injured. If you're lucky, the injury will only be a muscle pull or strain, in which the muscle is only slightly torn. Muscles can, unfortunately, be damaged more severely. The good news is that muscles, because of their good blood supply, tend to heal fairly quickly.
Our final stops on this tour of the back will be the facet joints and the nerves. Then, once we have all the parts laid out and explained, we will tell you how they all work together. Keep reading to learn more.
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.